The present invention relates to a process and an apparatus for the automatic manufacturing of different toric optical lenses. More specifically, the invention relates to the automatic manufacturing of different toric ophthalmic lenses, such as contact lenses.
It is known to produce optical lenses, in particular ophthalmic lenses such as contact lenses in a fully automated manufacturing process. One example for such a process is known, for example, from WO 98/42497. In this process, a plurality of molds—e.g. ten molds—are arranged in one mold carrier, each mold comprising a male mold half and a female mold half. The mold carrier comprises two mold carrier members in which the mold halves are arranged in two rows of five columns, respectively, the male mold halves being arranged in one of the mold carrier members and the female mold halves being arranged in the other mold carrier member. The two mold carrier members are pivotally connected with each other, and the molds can be closed by pivoting the one carrier member—e.g. that one carrying the male mold halves—about a pivot axis until the male mold halves arranged therein mate the corresponding female mold halves arranged in the other carrier member. Embodiments of the male and female mold halves which can be used in such a process are shown, for example, in WO 03/035376.
Toric contact lenses are well-known for the correction of astigmatism. However, due to the large varieties of astigmatism (in particular with respect to the relative position of the meridians as well as with respect to the amount of cylindrical corrective power), the number of one specific type of toric contact lens to be produced—i.e. of a contact lens having one specific relative position of the meridians and having one specific amount of cylindrical corrective power—is not as high as this is the case for contact lenses having only spherical corrective power. Accordingly, in the automatic manufacturing of toric contact lenses the shaping surfaces of the male and female mold halves defining the geometry and corrective power of the contact lens to be produced can only be used for producing a comparatively limited number of toric contact lenses of the same specific type.
Once the desired number of a specific type of toric contact lens has been produced and it is desired to produce a different specific type of toric contact lens the male and female mold halves have to be rotated relative to one another (assuming that only the rotational orientation of the male and female mold halves has to be changed). For that reason, the mold carriers have to be removed from the automatic production line in order to perform the desired relative rotation of the male and female mold halves. This rearrangement of the mold halves involves a significant expense, since the mold carriers have to be removed from the production line first and, accordingly, production has to be interrupted. The mold halves which are fixed in the respective members of the mold carriers removed from the production line then have to be released, rearranged (rotated relative to one another) and have to be precisely adjusted relative to one another again. After the rearrangement (relative rotation of the male and female mold halves) and the precise adjustment have been performed it is necessary to return the mold carriers to the production line and to run-in the rearranged molds on the production line under the conditions present in the production line (e.g. relative humidity, etc.), which means that a number of sample lenses have to be manufactured to make sure that the quality of the lenses produced with the rearranged molds is always satisfactory. These sample lenses must be discarded an cannot be distributed to consumers, and only after having performed the running-in of the rearranged molds on the production line, actual production of lenses using the rearranged molds can be resumed.
Accordingly, it is an object of the present invention to suggest a process and an apparatus which are suitable to prevent the afore-mentioned disadvantages and to allow comparatively low numbers of toric optical lenses of one specific type to be produced in an automatic lens manufacturing line and then to produce optical toric lenses, in particular toric ophthalmic lenses such as contact lenses, of a different type using the same molds.